In Electronics A2, we were playing around with 2N7000 MOSFETs. We had a very high failure rate with only me and two other people getting good results. We were trying to measure their transconductance by varying the gate voltage and measuring the current, up to 22mA (through a 220 ohm resistor.) However most people had the problem where the MOSFET was always conducting current no matter what the gate voltage was.
I got mine working, but then I disconnected the gate lead briefly with my fingers; when I plugged it back in, it was dead (shorted.) My teacher is convinced that we are exceeding the power dissipation of the MOSFETs with a 22mA current, but I showed him that it was unlikely as it would only heat up by about 5°C. I'm thinking ESD as that is the only thing which explains why my handling of the gate lead blew it up.
Anyone else experienced these problems?
I got mine working, but then I disconnected the gate lead briefly with my fingers; when I plugged it back in, it was dead (shorted.) My teacher is convinced that we are exceeding the power dissipation of the MOSFETs with a 22mA current, but I showed him that it was unlikely as it would only heat up by about 5°C. I'm thinking ESD as that is the only thing which explains why my handling of the gate lead blew it up.
Anyone else experienced these problems?